ECONOMICAL AND PHYSIOLOGICAL VALUE. 233 



The second above-mentioned condition of success in feed 

 ing, serving as a qualification of the chemical analysis of the 

 fodder, necessitated more actual feeding experiments to arrive 

 at more correct conclusions regarding their relative amount 

 of digestible substances. From forty-five to fifty fodder sub- 

 stances have already been studied more or less in that direc- 

 tion. 



A natural consequence of these investigations has been, 

 that our notions regarding the valuation of a fodder sub- 

 stance are somewhat modified as compared with former 

 periods: we distinguish between the economical value of an 

 article of fodder and its physiological value. The former 

 finds its expression in the market-price, which, in every case, 

 may be stated by a definite amount of money, and depends 

 upon demand and supply in the general market. The latter 

 depends upon the particular feeding effect the article pro- 

 duces. As this effect, for obvious reasons, will vary under 

 different circumstances, depending largely on a judicious 

 application of the article, it can be represented by but one 

 numerical value. The best financial success in feeding ope- 

 rations can only be secured by taking both standard's into 

 consideration. 



To illustrate the previous statements, the following ex- 

 periment of Dr. Knop, a distinguished German agricultural 

 investigator, which Grouven cites for a similar purpose, may 

 not be without interest here. A cow weighing one thousand 

 pounds had been fed for some time with twenty -six pounds 

 of potatoes, two pounds and a half of oil-cakes, and fourteen 

 pounds of hay, per day, without changing her weight ; as 

 soon as one more pound of oil-cake per day had been added, 

 her weight increased quite rapidly ; within fourteen days 

 she had gained ninety-one pounds in weight. This result 

 cannot be satisfactorily explained by the mere increased con- 

 sumption of fourteen pounds of oil-cake ; but it is reason- 

 able to suppose that the excess of starch due to a too lib- 

 eral use of potatoes was turned to a better account for the 

 formation of animal matter, instead of passing largely into 

 the excretions of the animal. The physiological value of 

 the fourteen pounds of oil-cake exceeded many times their 

 commercial value. 



One of the great services which Grouven rendered to 



